仅在部分课程中声明变量

Question

Let's say we have a class like:

class House {
    street: string;
    pools: number;
    helicopterLandingPlace: boolean;
}

Now i build a service to update my house.

putHouse(house: House) {
    // some put request
}

But sometime I expect just parts of the house to get updated.

patchHouse(house: ?????) {
    // some patch request...
}

What is the cleanest way to declare the variable house with in the second function.

Thanks in advance for your help!

Answer 1

One way to accomplish this would be by using the Partial type, something like:

 class House { street: string; pools: number; helicopterLandingPlace: boolean; } function patchHouse(house: Partial<House>) { console.log(house); } patchHouse({street: 'street'}); 

Under the hood

Partial<T> is an interface that has the following definition:

type Partial<T> = { [P in keyof T]?: T[P]; };

Which means that by using the keyof operator we get something like:

Partial<House> {
  street: string?;
  pools: number?;
  helicpterLandingPlace: boolean?;
}

Answer 2

Interface segregation :

interface Addressable {
    street: string;
}

interface Swimmable {
    pools: number;
}

interface Landable {
    helicopterLandingPlaces: boolean;
}

class House implements Addressable, Swimmable, Landable {
    street: string;
    pools: number;
    helicopterLandingPlaces: boolean;
}

function patch(house: Swimmable) {
    house.pools++;
}